Soft-solder suction devices of this kind are used, inter alia. for connecting components to circuit cards or boards. In the case of circuit cards or circuit boards, it is important that the molten solder does not spread on the card or board, since this may cause short-circuiting between the closely packed components. In this respect, when effecting a soldering operation the workman manoeuvres a soldering iron, or like tool, with one hand, while holding a soft-solder suction device in his/her other hand, with the tip of the suction device located close to the soldering location. Immediately the soft solder has been brought to a molten state, with the aid of the soldering iron, the suction device is activated by releasing the piston, whereupon surplus solder is automatically drawn into the suction pipe. In order for this operation to be successful, it is extremely important that the suction device is held steady and in the correct position of alignment with respect to the soldering location, when the piston is released.
In the majority of soft-solder suction devices of the aforesaid kind used today, the piston is driven through the cylinder by the force of a spring. This mode of operation has a number of serious drawbacks and disadvantages. Among other things, the use of a spring means that the piston must be moved manually to its starting position, i.e. cocked, prior to each suction operation, while tensioning the spring. This constitutes an interruption in the smoothness of the soldering work. Furthermore, the task of manually cocking the piston can be a relatively difficult one to carry out, since a relatively large force must be applied to tension a spring of the strength required to move the piston at a speed sufficient to generate an effective suction effect.
Consequently, this manual cocking of the piston sets a limit on the strength of the spring that can be used.
A more serious drawback is that in order to release the spring force, so as to draw up excess solder, it is necessary to move the hand holding the suction device, which unavoidably results in some small movement of the device. This movement is liable to cause such misalignment of the device that not all of the molten solder is drawn into the suction pipe. Misalingment of the device can also be caused by the recoil action of the piston, when said piston is released. The use of a spring also results in irregular movement of the piston, since the piston is rapidly retarded as the spring force decreases, towards the end of the piston stroke. Consequently, this results in an irregular suction effect.
In an attempt to eliminate these disadvantages and drawbacks encountered when using a spring in accordance with the aforegoing, it has been suggested that a soft-solder suction device is connected to a suction vessel. Because of the limited subpressures attainable in practice, and because of the volume of the requisite suction lines, the proposed arrangement does not produce a sufficiently powerful suction effect immediately the suction device is activated.
A further disadvantages with known molten-solder devices of the kind mentioned in that molten solder is sucked into the path travelled by the piston, where the solder fastens and impairs the seal between piston and cylinder. Thus, these known devices must be cleaned quite frequently, which is a time-consuming task, since in order to be cleaned the device must be stripped down, causing interruptions in productivity.